The conventional porosity measurement is not adequate to precisely measure “as-is” porosity of heavy oil sand samples due to its irregular sample shape, pore-filling viscous fluids, and especially difficult storage without losing mass. From a practical laboratory point of view, a confined porosity measurement strategy is specifically introduced to measure the as-is porosity of heavy oil sand sample. This overall strategy primarily consists of two parts. First of all, as-is porosity is estimated by using the assumed parameters (grain density, fluid density, and fluids saturation) and measured bulk density that is calculated from the Archimedes principle, which not only keeps the sample intact, but also is advantageous for minimizing mass loss and external covers. Furthermore, by extracting the pore fluids (heavy oil, water, and possibly gas) from the original sample, the assumed indispensable parameters are precisely measured; more importantly, a group of porosity data can be calculated by applying directly measured grain volume data and bulk volume data. Based on the measured data and error analysis, we have concluded that the porosity calculated from these directly measured data set gives us a low porosity bound whereas as-is porosity estimated from the Archimedes principle indicates the upper bound.